10.1.10.6 The utf8mb3 Character Set (Alias for utf8)

In a future version of MySQL, it is possible that
utf8 will become the 4-byte
utf8, and that users who want to indicate
3-byte utf8 will have to say
utf8mb3. To avoid some future problems
which might occur with replication when master and slave
servers have different MySQL versions, it is possible for
users to specify utf8mb3 in
CHARACTER SET clauses, and
utf8mb3_collation_substring
in COLLATE clauses, where
collation_substring is
bin, czech_ci,
danish_ci, esperanto_ci,
estonian_ci, and so forth. For example:

MySQL immediately converts instances of
utf8mb3 in an alias to
utf8, so in statements such as
SHOW CREATE TABLE or SELECT
CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.COLUMNS
or SELECT COLLATION_NAME FROM
INFORMATION_SCHEMA.COLUMNS, users will see the true
name, utf8 or
utf8_collation_substring.

The utf8mb3 alias is valid only in
CHARACTER SET clauses, and in certain other
places. For example, these are legal:

mysqld --character-set-server=utf8mb3
SET NAMES 'utf8mb3'; /* and other SET statements that have similar effect */
SELECT _utf8mb3 'a';

There is no utf8mb3 alias to the
corresponding utf8 collation for collation
names that include a version number (for example,
utf8_unicode_520_ci)
to indicate the Unicode Collation Algorithm version on which
the collation is based.